September 20, 2014

Extreme Weather Watch: April 2014 - Tornadoes, Flash Floods Pound US

The last week in April saw extreme weather over as much as half the nation. Over 20 states were affected. In some places a month's worth of rain fell in a day. In New York City there was close to 5 inches of rain in one day. In Pensacola, FL there was over 20 inches of rain in 24 hours, 6 inches in one hour alone, more rain than Los Angeles saw all last year. More rain fell in Pensacola than during Hurricane Ivan. There were nearly 6000 lightning strikes in fifteen minutes. First responders rescued people in boats. Roads and bridges collapsed.

Two trillion gallons of water fell on the south and the east coast in just one day. Flooding was worse than after some hurricanes. Heavy rain led to the collapse of a retaining wall in a Baltimore neighborhood sending cars tumbling 75 feet down an embankment onto railroad tracks. These cars were not covered by insurance as the collapsing embankment was considered an "act of God." The Schuylkill River in Philadelphia crested higher than after Hurricane Irene and Super Storm Sandy. Philadelphia received more rain in a day than it usually gets in a month. Golf ball sized hail pummeled the country.

Small towns in some states were wiped off the map. A violent high-end EF-4 tornado with winds of 180 - 190 mph tore through Vilonia and Mayflower, AK on April 27, killing 15 people. A whole neighborhood in Vilonia, which was hit by a tornado just 3 years ago, was wiped out. A brand new school costing $14 million was reduced to a pile of rubble. This tornado was also the widest (3/4 mile) and longest lived (60 minutes) twister of the outbreak. It was on the ground for almost 100 miles.

In Tupelo, MS an EF-3 tornado destroyed an entire business district and sent trees crashing into houses. Peak estimated wind speeds were 150 mph and the path length was at least 24 miles. The tornado lasted over 26 minutes. In Louisville, MS a tornado rated EF-4 with peak estimated wind speeds of 190 mph, a maximum width of 0.75 mile and a path length of 35.5 miles over 56 minutes left 9 dead and a hospital heavily damaged.

But this was not the only extreme weather event in April. On April 4 the National Weather Service reported a number of twisters across several states. More than two feet of rain caused flooding problems for Gulf Coast communities just days after a severe weather outbreak brought multiple tornadoes to Alabama. There were at least 30 water rescues in the Mobile area alone.

Emergency managers say at least 240 homes were damaged or destroyed by the tornadoes and strong storms that swept through Alabama in early April. An update from the Alabama Emergency Management Agency said that damage was reported in 31 of Alabama's 67 counties.

St. Louis, MO residents awoke April 3 to tornado sirens as a cluster of heavy thunderstorms began moving through. A tornado was spotted around 8:16 PM on the ground in St. Louis County near Glendale. About an hour earlier, the agency reported a "damaging" twister with quarter-size hail about 50 miles west near Washington. And a tornado was earlier reported in the Osage County community of Rich Fountain. The weather service confirmed a tornado touched down about an hour before sunrise in the St. Louis suburb of University City, gouging a half-mile-by-100-yard path. The weather service gave the tornado, packing top winds of 112 miles per hour, an initial rating of EF-1.

In the west there were wildfires as Santa Ana winds topped 100 mph in some places including San Diego County and temperatures approached 100 degrees F. There have already been 1000 wildfires in California this year and fire season has barely gotten underway. More than 1600 homes were evacuated in Rancho Cucamonga as a fire charred 2000 acres.

It's not necessary to have actual tornadoes in order to inflict massive damage as high winds, torrential rains and golf ball sized hail, which is increasingly common during thunderstorms, can cause downed tree limbs, roof and gutter damage and busted windows. A forthcoming National Climate Assessment report shows that the top 1% rain events have increased in all regions of the continental US in the past five decades due to climate change.

There have already been three weather disasters this year which will cost over $1 billion:

1) The January 5 - 8 "Polar Vortex" winter weather outbreak, which is estimated to cost $3 billion in damage.

2) The California drought, with $3.6 billion in agricultural damages so far, as estimated by the California Farm Water Coalition.

3) Severe weather outbreak of April 27 - 30, which is estimated to cost over $1 billion in damage.

The return of tornado season with a vengeance has people asking again about a possible link to climate change. At the same time, tantalizing new preliminary research finds “some evidence to suggest that tornadoes are, in fact, getting stronger.”

Tom Karl, the director of the National Climatic Data Center, explained in a 2011 email:

What we can say with confidence is that heavy and extreme precipitation events often associated with thunderstorms and convection are increasing and have been linked to human-induced changes in atmospheric composition.